docs: def analyse_text(text):
          """
          Recognize JCL job by header.
          """
          result = 0.0
          lines = text.split('\n')
          if len(lines) > 0:
              if JclLexer._JOB_HEADER_PATTERN.match(lines[0]):
                  result = 1.0
          assert 0.0 <= result <= 1.0
          return result